Fix integration tests in src/chrome and src/extensions so that we can turn on IO thread checks wi...

chrome/browser/ui/webui/test_files_request_filter.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/test_files_request_filter.h"
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/path_service.h"
 #include "base/strings/string_split.h"
+#include "base/threading/thread_restrictions.h"
 #include "chrome/common/chrome_paths.h"
 
 namespace {
 
 bool HandleTestFileRequestCallback(
     const std::string& path,
     const content::WebUIDataSource::GotDataCallback& callback) {
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   std::vector<std::string> url_substr =
       base::SplitString(path, "/", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
   if (url_substr.size() != 2 || url_substr[0] != "test")
     return false;
 
   std::string contents;
   base::FilePath test_data_dir;
   PathService::Get(chrome::DIR_TEST_DATA, &test_data_dir);
   if (!base::ReadFileToString(
           test_data_dir.AppendASCII("webui").AppendASCII(url_substr[1]),
           &contents))
     return false;
 
   base::RefCountedString* ref_contents = new base::RefCountedString();
   ref_contents->data() = contents;
   callback.Run(ref_contents);
   return true;
 }
 
 }  // namespace
 
 namespace test {
 
 content::WebUIDataSource::HandleRequestCallback GetTestFilesRequestFilter() {
   return base::Bind(&HandleTestFileRequestCallback);
 }
 
 }  // namespace test